Okrum is a Windows backdoor/implant associated with APT15. The provided content places it in APT15’s malware arsenal alongside MirageFox and notes it has also been referenced with other APT15 tooling such as RoyalCLI, RoyalDNS, and Ketrum. Okrum supports persistence by creating a scheduled task and by installing itself as a Windows service, including use of the service name NtmsSvc/NtmSsvc to execute the payload. Its loader can decrypt the backdoor code either from data embedded in the loader itself or hidden in a legitimate PNG file, using either a custom XOR cipher or RC4. For command and control, Okrum uses HTTP requests, can identify victim-configured proxy servers and use them for C2 communications, has used Base64 to encode C2 traffic, and uses AES to encrypt network traffic, with the key either hardcoded or negotiated during registration with the C2 server. The malware can collect victim information including the username and system date/time, and it has been observed using NetSess to discover NetBIOS sessions. Okrum was also seen using MimikatzLite for credential dumping and a RAR archiver tool to compress or decompress data. For exfiltration, it stores logs and command output in hidden files before sending data over the existing C2 channel, and its backdoor deletes files after successful upload to C2 servers.
Mallory pivots from this family to the IOCs, detections, and named campaigns that touch your stack, and pages you when something new lands.
1 distinct threat actor attributed by public researchers. Open in Mallory to see the full evidence chain and overlapping campaigns.
APT15's arsenal includes tools for both Windows (Okrum, MirageFox) and Android
22 distinct techniques documented for this family, organized by ATT&CK tactic.
“Sandworm Team leveraged Scheduled Tasks through a Group Policy Object (GPO) to execute CaddyWiper at a predetermined time.” / “APT29 used scheduler and schtasks to create new tasks on remote host as part of their lateral movement… updating an existing legitimate task to execute their tools and then returned the scheduled task to its original configuration.”
During the 2022 Ukraine Electric Power Attack, Sandworm Team leveraged Scheduled Tasks through a Group Policy Object (GPO) to execute CaddyWiper at a predetermined time.
During the 2016 Ukraine Electric Power Attack, Sandworm Team used the xp_cmdshell command in MS-SQL. During the 2025 Poland Wiper Attacks, the adversaries leveraged PsExec to run cmd.exe commands on multiple victim machines. Numerous malware families and groups are described as using cmd.exe, cmd /c, Windows command shell, or command-line interfaces to execute commands, payloads, reconnaissance, persistence, cleanup, and ransomware actions. | APT1 has used the Windows command shell to execute commands, and batch scripting to automate execution. Blue Mockingbird has used batch script files to automate execution and deployment of payloads. During HomeLand Justice, threat actors used Windows batch files for persistence and execution.
“Sandworm Team leveraged Scheduled Tasks through a Group Policy Object (GPO) to execute CaddyWiper at a predetermined time.” / “APT29 used scheduler and schtasks to create new tasks on remote host as part of their lateral movement… updating an existing legitimate task to execute their tools and then returned the scheduled task to its original configuration.”
During the 2022 Ukraine Electric Power Attack, Sandworm Team leveraged Scheduled Tasks through a Group Policy Object (GPO) to execute CaddyWiper at a predetermined time.
During the 2016 Ukraine Electric Power Attack, Sandworm Team used an arbitrary system service to load at system boot for persistence for Industroyer. They also replaced the ImagePath registry value of a Windows service with a new backdoor binary.
“Sandworm Team leveraged Scheduled Tasks through a Group Policy Object (GPO) to execute CaddyWiper at a predetermined time.” / “APT29 used scheduler and schtasks to create new tasks on remote host as part of their lateral movement… updating an existing legitimate task to execute their tools and then returned the scheduled task to its original configuration.”
During the 2022 Ukraine Electric Power Attack, Sandworm Team leveraged Scheduled Tasks through a Group Policy Object (GPO) to execute CaddyWiper at a predetermined time.
During the 2016 Ukraine Electric Power Attack, Sandworm Team used an arbitrary system service to load at system boot for persistence for Industroyer. They also replaced the ImagePath registry value of a Windows service with a new backdoor binary.
Aquatic Panda created new Windows services for persistence that masqueraded as legitimate Windows services via name change.
Several entries explicitly state files were deleted after exfiltration or upload, such as 'AppleSeed can delete files from a compromised host after they are exfiltrated,' 'Attor’s plugin deletes the collected files and log files after exfiltration,' and 'Ursnif has deleted data staged in tmp files after exfiltration.' | The content repeatedly describes adversaries and malware deleting files, directories, droppers, scripts, logs, archives, staged data, and other artifacts from compromised systems, e.g., 'APT29 has used SDelete to remove artifacts from victim networks' and 'Lazarus Group malware has deleted files in various ways, including "suicide scripts" to delete malware binaries from the victim.'
The content repeatedly describes malware and threat actors decoding, decrypting, deobfuscating, or unpacking payloads, strings, configuration data, commands, and C2 responses prior to execution or use.
Agent Tesla has created hidden folders. AppleJeus has added a leading . to plist filenames, unlisting them from the Finder app and default Terminal directory listings. APT28 has saved files with hidden file attributes. FIN13 has created hidden files and folders within a compromised Linux system /tmp directory and also used attrib.exe to hide gathered local host information.
Multiple actors and tools are described as using Mimikatz/Windows Credential Editor/LaZagne/ProcDump to “dump credentials,” often by targeting LSASS memory (e.g., “used Mimikatz to capture and use legitimate credentials,” “dumped the LSASS process memory using the MiniDump function,” “injecting itself into lsass.exe”).
The content repeatedly describes malware and threat actors using commands and APIs such as ipconfig /all, ifconfig, arp -a, route print, nbtstat, netsh, GetAdaptersInfo, and GetIpNetTable to gather IP addresses, MAC addresses, DNS, DHCP, gateways, routing tables, ARP cache, proxy settings, domains, and network adapter/interface details.
The content repeatedly describes malware and threat actors collecting usernames, identifying logged-in users, running whoami/query user/quser, checking whether the current user is an administrator, enumerating user sessions, and gathering account details from compromised hosts.
The content is a long ATT&CK-style listing of malware and threat actors that collect host details such as OS version, hostname, architecture, CPU, memory, BIOS, language, and other basic system characteristics; examples include use of commands like systeminfo, ver, uname, sw_vers, and WMI queries.
The content repeatedly describes malware and threat actors listing files and directories, enumerating drives, searching for files by extension/name/path, retrieving file metadata, and browsing file systems (for example: "APT28 has used Forfiles to locate PDF, Excel, and Word documents during collection" and "cmd can be used to find files and directories with native functionality such as dir commands").
Multiple actors and tools are described as using 7-Zip/WinRAR/zip/tar/gzip/makecab/PowerShell Compress-Archive to compress (often password-protect/encrypt) collected data prior to exfiltration (e.g., “used 7zip to archive extracted data in preparation for exfiltration”, “created password-protected RAR archives prior to exfiltration”, “used built-in PowerShell capabilities (Compress-Archive cmdlet) to compress collected data”).
The content repeatedly describes threat actors and malware using HTTP and HTTPS for command and control, such as: "Sandworm Team used BlackEnergy to communicate between compromised hosts and their command-and-control servers via HTTP post requests."
APT28 used other victims as proxies to relay command traffic, for instance using a compromised Georgian military email server as a hop point to NATO victims.
C2 traffic from ADVSTORESHELL is encrypted, then encoded with Base64 encoding... APT19 HTTP malware variant used Base64 to encode communications to the C2 server... APT33 has used base64 to encode command and control traffic.
"3PARA RAT command and control commands are encrypted within the HTTP C2 channel using the DES algorithm in CBC mode..."; "APT33 has used AES for encryption of command and control traffic."; "Carbanak encrypts the message body of HTTP traffic with RC2 (in CBC mode)."; "Duqu ... data stream can be encrypted with AES-CBC."; "PoisonIvy uses the Camellia cipher to encrypt communications."
ADVSTORESHELL exfiltrates data over the same channel used for C2... Agrius exfiltrated staged data using tools such as Putty and WinSCP, communicating with command and control servers... numerous malware and groups sent victim data, files, credentials, or host information over existing C2 channels.
45 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Okrum is a backdoor malware used by APT15, notable for using steganography to conceal payloads within PNG images.
Windows malware used by APT15 for malicious access and espionage operations.
Custom APT15 implant/backdoor referenced as part of the group’s historical tooling.
Backdoor whose installer attempts persistence via scheduled tasks.
Match every observed IP, domain, and hash against your live telemetry.
Named campaigns wielding this family, with evidence pinned to each claim.
CVEs this family uses for access and lateral movement.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Every documented technique, ranked by evidence weight.
Reddit, Mastodon, and CTI community discussion around this family.